1. Field of the Invention
This invention relates to a recording or reproducing apparatus and more particularly to the loading action of a recording medium loading mechanism.
2. Description of the Related Art
The conventional recording or reproducing apparatuses include a cassette-biting type magnetic recording or reproducing apparatus which is arranged to allow a drum thereof to intrude (bite) into a recessed part provided in the cassette of a recording medium for the purpose of reduction in size of the apparatus. Referring to FIG. 1, the apparatus of this type is provided with two chassis, i.e., a main chassis 1 and a slide chassis 3. A slide gear 5 is interlocked with a loading motor (not shown) and rotates when the loading motor rotates. A slide pin 6 is secured to the slide gear 5. A slide plate 7 is secured to the slide chassis 3. A power for moving the slide chassis 3 is derived from the rotation of the slide gear 5 which causes a sliding movement of the pin 6 along the inner side of a slot formed in the slide plate 7. When the slide chassis 3 moves, slide slots 11 and 12 formed in the slide chassis 3 are respectively guided by slide guide shafts 8 and 9 which are secured to the main chassis 1. This arrangement enables the slide chassis 3 to move in the directions of sliding as shown in FIG. 1. Shafts 10 and 20 and slots 13 and 23 are provided for restricting the position of the slide chassis 3 in the direction of its height when the chassis 3 moves, and are not directly used as guides for the movement of the chassis 3.
With the conventional apparatus arranged in the above-stated manner, when the slide chassis 3 slides in the direction of moving away from a rotary head drum 2, a load moment Ma comes to be imposed on the slide guide shaft 8 due to a lever 4 which is pivotally arranged on the slide chassis 3. Then, a driving force Fa for the slide chassis 3 brings forth a moment Mb centering on a connection point between the slide guide shaft 8 and the lever 4. At this instant, a force F which is as shown in FIG. 2 is applied to the slide guide shaft 9. In order to allow the slide chassis 3 to slide, a condition which is expressed as Fb&gt;.mu.N is necessary. In the condition, ".mu." represents a coefficient of friction; N=Fcos.THETA.; and Fb=Fsin.THETA.. The limit value of the coefficient of friction .mu. is calculated as follows: since Fb&gt;.mu.N, there obtains a relation .mu.Fcos.THETA.&lt;Fsin.THETA. therefore, .mu.&lt;tan.THETA.. The limit value of the coefficient of friction .mu. is thus determined by an angle .THETA. which is defined by the force F and the slide slot 12.
In the conventional apparatus, as described above, the angle .THETA. defined by the force F and the slide slot 12 is small. Therefore, an operable coefficient of friction becomes small. Changes occurring through a long service period would cause the actual coefficient of friction to easily exceed an operable range of the coefficient of friction. As a result, the action to cause the slide chassis 3 to slide has often been performed faultily. The occurrence of the faulty sliding action newly brings forth an additional moment which centers on a connection point between the slide guide shaft 9 and the slide slot 12 in the direction of the moment Mb. The additional moment then causes a malfunction to further hinder the movement of the slide chassis 3.